Some types of fixed subarray connections have been studied in [1]}, where it was shown that type “Squared” achieves better sum-rate than other types. Thus, we set \(\mathbf {S}_{\sf {FSA}}\)  to the “Squared” connection pattern. The general approach described in (REF ) can be considered here as well. In [2]}, a solution called “CR-AltMin” proposed to design the FSA-HBF. We used this method as a point of comparison for our DL solution.
